1. Field of the Invention
Embodiments of the present invention relate to low molecular weight conjugated nitrogen compounds and devices fabricated using the conjugated nitrogen compounds. More particularly, embodiments of the present invention relate to low molecular weight conjugated nitrogen compounds having linear conjugated chains, and devices fabricated using the conjugated nitrogen compounds as organic semiconductor materials, hole conducting materials, or light-emitting materials.
2. Description of the Related Art
Recent research has been concentrated on low molecular weight organic materials, such as pentacene, as organic semiconductor materials, and some research groups have paid attention to high molecular weight organic materials.
Although low molecular weight organic materials, e.g., pentacene, have been reported to have a high charge carrier mobility and a high on/off current ratio (Ion/Ioff ratio), they necessitate the use of expensive vacuum deposition apparatuses for fabricating devices and have a difficulty in forming fine patterns. Accordingly, low molecular weight organic materials are not attractive for the manufacture of large-area displays at low costs.
Unlike low molecular weight organic materials, polythiophene-based high molecular weight organic materials are easily formed into solutions, and can be formed into thin films by screen printing, ink-jet and roll printing techniques. For these reasons, it is reported that the high molecular weight organic materials have advantages in the manufacture of large-area displays at low costs.
However, since the high molecular weight organic materials have different oxidation potentials depending on their molecular weight distribution, which is a cause of instability, their application to the fabrication of devices presents considerable difficulties. In contrast, since the low molecular weight organic materials have a constant oxidation potential, they have been found to be advantageous in terms of stability.
Additionally, low molecular weight materials, e.g., tris-(8-hydroxyquinoline)aluminum (Alq), and high molecular weight materials, e.g., polyphenylenevinylene (PPV) and polyalkylthiophene (PAT), have been known as light-emitting materials. Like the above-mentioned organic semiconductor materials, low molecular weight light-emitting materials cannot be spin-coated at room temperature, while high molecular weight light-emitting materials can be coated by spin coating at room temperature. High molecular weight light-emitting materials still have the problem of instability.